The present invention relates generally to communication systems and methods of communication, and, especially, to communication systems and methods of communication for use in magnetic resonance imaging procedures.
In general, magnetic resonance imaging (MRI) systems require isolation from external sources of electromagnetic fields to optimize image quality. Conventional MRI systems, therefore, typically include some form of electromagnetic isolation shield or barrier. Most often, a room enclosed by copper sheeting or conductive mesh material isolates or shields the imaging system from undesirable sources of electromagnetic radiation, including the electromagnetic noise inherent in the atmosphere.
A number of powered injectors for use in MRI have been developed. These powered injectors are a potential source of electromagnetic radiation. To realize the full benefit of “shielded” rooms in MRI, injector systems typically employ a controller that is isolated from the powered injector. For example, the controller may be placed outside of a shielded room (e.g., in the MRI control room) in which the MRI scanner and the powered injector operate. Such isolation prevents undesirable electromagnetic radiation generated by the injector system controller from interfering with the signals used to create the magnetic resonance images.
The external, isolated location of the system controller creates various problems associated with the installation and operation of these systems. One such problem is the need to provide a communication link between the external controller and the injector (which is located within the shielded area), without introducing extraneous electromagnetic radiation. In other words, there is a need to provide injector control circuitry while maintaining the integrity of the electromagnetic shield.
Previous attempts to solve these problems included drilling holes in the wall of the electromagnetic shield for inserting the necessary lines or, alternatively, laying the lines under a shielded floor of the imaging room. These alternatives have proven to be less than optimum, since spurious radiation can arise from the presence of the various supply cables within the shielded imaging suite. Additionally, MRI systems, which employ these alternatives often, require substantial site dedication and are, therefore, not very portable.
U.S. Pat. No. 5,494,036, the disclosure of which is incorporated herein by reference, discloses, in one embodiment, an improved communication link that is made through a window in an isolation room barrier. These windows are typically in the form of a glass laminate containing a conductive wire mesh, or alternatively, a window that is coated with a thin sheet of conductive material such as gold to maintain the shielding characteristics of the isolation area or room.
The above-noted embodiment of the communications link of U.S. Pat. No. 5,494,036 includes electromagnetic transceivers that operate in a frequency range which permeates the window while maintaining the integrity of the isolation barrier. The internal transceiver is positioned on the window and is tethered or attached to the injector control in the MRI shielded room via a communication line. The external transceiver is positioned on the opposite side of the window (i.e., in the MRI control room) and is connected to the injector system controller. Infrared or electromagnetic energy in the visual range are noted to provide the best results. A fiber optic communication link is also disclosed.
Although improvements have been made in communication systems for use in magnetic resonance imaging, it remains desirable to develop improved communication systems.